The disclosed invention relates to ink jet printing systems, and more particularly to increasing the usable life of ink firing heater resistors.
Ink jet printing systems commonly make use of an ink jet printhead that is moved relative to a print medium such as paper. As the printhead is moved relative to the print medium, control electronics activate an ink drop generator portion of the printhead to eject or fire ink droplets from ejector nozzles and onto the print medium to form a printed image. An ink supply provides ink for the printhead.
Some ink jet printing systems employ an ink supply that is replaceable separately from the printhead. When such xe2x80x9coff-axisxe2x80x9d ink supply is exhausted, the ink supply (e.g., an ink cartridge) is removed and replaced with a new ink supply. The printhead is replaced at or near the end of the printhead life, and not when the ink supply is exhausted. When a replaceable printhead is capable of utilizing a plurality of ink supplies, this can be referred to as a xe2x80x9csemipermanentxe2x80x9d printhead, which is in contrast to a disposable printhead that is replaced with when the ink supply is replaced.
A consideration with semipermanent printheads is a desire for extended heater resistor life so that the printhead is replaced less frequently.
The disclosed invention is directed to an ink delivery system that allows air to be absorbed by ink that is being delivered to a thermal ink jet printhead so that ink delivered to the printhead has an air saturation of at least 30%. Alternatively, the ink delivered to the thermal ink jet printhead has an air saturation of at least 50% or 70%.